8. Basic aerodynamics - Q&A

Air above Mach 0.7 is

• partially compressible.
• incompressible.
• compressible.

As altitude increases, pressure

• decreases exponentially.
• reduces at a constant rate.
• rises exponentially.

If an aircraft is yawing left, the trim tab on the rudder would be positioned

• to the right, deflecting the rudder left.
• back to its neutral centre position.
• to the left, moving the rudder right.

An engine which produces an efflux of high speed will be

• less efficient.
• more efficient.
• unaffected by efflux speed.

Vortex generators are fitted to

• move transition point rearwards.
• move the transition point forwards.
• delay the onset of boundary layer separation.

Other than spoilers, where are speed brakes located?

• Underneath the fuselage belly near the main landing gear doors.
• Either side of the fuselage or on the wing.
• Mounted on the wing trailing edge inboard section.

Airflow over the upper surface of the wing generally

• flows toward the tip.
• flows towards the root.
• flows chordwise from leading to trailing edge.

What principle does the delta 3 hinge use?

• Triangular pitch lever.
• Flapping actuators.
• Offset hinges.

Sweepback increases Mcrit by

• decreasing the amount of airflow over the lowest point on the aerofoil section.
• decreasing the amount of airflow over the highest point on the aerofoil section.
• increasing the amount of airflow over the highest point on the aerofoil section.

Angle of attack on a down going wing in a roll

• increases.
• decreases.
• unaffected.

The trailing vorticity shed by a pointed wing (taper ratio = 0) is

• concentrated into a single strong tip vortex.
• shed almost entirely from the wing root.
• spread fairly evenly along the whole span.

Stall inducers may be fitted to a wing

• at the root to cause the root to stall first.
• at the tip to cause the root to stall first.
• at the root to cause the tip to stall first.

The maximum lift/drag ratio of a wing occurs

• at the angle of attack producing maximum total lift.
• during the take off ground roll.
• at an angle below which the wing develops max lift.

In normal flight conditions, an increase in aircraft speed

• causes the nose of the aircraft to drop.
• causes the nose of the aircraft to lift.
• the nose remains in the same position.

Tuck-under is caused by

• tip stall on a straight wing aircraft.
• tip stall on a swept wing aircraft.
• root stall on a swept wing aircraft.

What happens to air flowing at the speed of sound when it enters a converging duct?

• Velocity increases, pressure and density decreases.
• Velocity, pressure and density increase.
• Velocity decreases, pressure and density increase.

If you have an aircraft that is more laterally stable then directionally stable it will tend to

• bank.
• slip.
• skid.

During a climb from a dive

• the thrust required is greater than required for level flight.
• the thrust required is lower than for level flight.
• the thrust required is the same as for level flight.

The atmospheric zone immediately above the tropopause, where the temperature remains fairly constant, is called the

• stratosphere.
• ionosphere.
• troposphere.

A wing develops 10,000N of lift at 100knots. Assuming the wing remains at the same angle of attack and remains at the same altitude, how much lift will it develop at 300knots?

• 900,000N.
• 90,000N.
• 30,000N.

Downward displacement of an aileron

• increases the stalling angle of attack for that wing.
• decreases the angle at which its wing will stall.
• has no effect on its wing stalling angle, only on stalling speed.

On a high winged aircraft, what effect will the fuselage have on the up-going wing?

• The up-going wing will have a decrease in angle of attack and therefore a decrease in lift.
• The down-going will have a decrease in angle of attack and therefore a decrease in lift.
• The up-going wing will have an increase in angle of attack and therefore a decrease in lift.

In a bank, the weight is

• increased.
• decreased.
• unchanged.

The reason for sharp leading edged wings on high speed aircraft is to

• enable the shockwave to be accurately positioned.
• enable the shockwave to stand detached ahead of the wing.
• reduce the laminar boundary layer thickness on the wing surface.

The temperature to which humid air must be cooled at constant pressure to become saturated is called

• relative humidity.
• dew point.
• absolute humidity.